BBS: Inland Empire Archive
Date: 11-19-92 (02:35) Number: 313
From: RAYMOND KEITH Refer#: NONE
To: RICH GELDREICH Recvd: NO
Subj: Re: Challenge! Conf: (2) Quik_Bas
Your basicly updating the color palette while the display is in a horizontal
(1) The Input Status #1 register through port &H3DA gives you access to
the VR field (Vertical Retrace) and the DE field (Display Enable NOT).
These will let you know when to update the palette.
(2) &HC7 is the Pel address read mode register which
contains the eight bit address used to access one of the
256 color registers during a read opteration.
(3) &HC8 is the Pel Address write mode register which contains the eight bit
address used ot access one of the 256 color registers
during a write operation.
(4) &HC9 is the Pel data register which is a 18 bit wide register used to
interface the host and the 256 color registers. Each color register can hold
the primary colors, Red, Green, Blue. Each takes 6 bits. Since the host data
bus is only 8 bits you can only change one color at a time. The registers
above through &HC7 and &HC8 note which color register is
being read or written to with the data in this register.
Well you get the idea, wait for a horizontal retrace period, then change
a color, etc. Rich I think that is what your doing. If not, my answer is
surely techy looking enough to fool some people. <wide smile>
--- DB 1.37/003468
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